1. Field of the Invention
The present invention relates to thickened oxidant compositions, having both viscous and elastic properties, and in particular to thickened bleach compositions which are formulated to pour easily and flow through a narrow orifice or trigger spray bottle. The compositions also provide improved cling to vertical surfaces, such as toilet bowls.
2. Description of the Related Art
Hard surface cleaners are often thickened to provide to the consumer some control over the product during application, and to cling to the surface for some time after application in order to increase the contact time of the cleaning components. Furthermore, such thickened products are often put into packages with a closure that constricts the product to squeeze out in a narrow stream, for even more powerful and controllable product flow during application.
Consumer preferred products of this type therefore must have optimum flow properties under both dispensing and surface coating conditions. Products require ease of squeezing and projecting a fluid stream onto a surface. Products additionally require effectiveness of product coating and clinging to a surface. This optimization requires a balance. With too little thickening, the product will drain too quickly and result in insufficient perceived cling. With too much thickening, the product could result in dispensing problems or non-uniform coating.
A typical approach by those skilled in the art targets a higher product viscosity at low shear rates to ensure adequate cling, combined with a lower product viscosity at high shear rates to ensure ease of dispensing. A formulator might thus look for chemistries that result in sufficiently shear-thinning products to hit such viscosity ranges at both low and high shear rates.
Such systems are generally not difficult to formulate, and examples can be found on the market. However, the products that exhibit the most consumer preferred rheology for dispensing and coating are the non-bleach systems, for which thickening formulation approaches are much broader than for bleach-containing systems. Manufacturers have not been able to achieve the same optimum aesthetics with bleach-containing systems, which are commonly thickened with bleach stable surfactants, even though these formulations might be within the target viscosity ranges at low and high shear rates.
Formulators attempting to make improvements to product cling are most likely to make changes that increase the viscosity at low shear rate. This often has the effect of also increasing elasticity, and can actually negate any gains made to perceived cling by the increased viscosity. Alternatively, formulators may incorporate a component that forms weak interactions with the thickening system, which adds to the viscosity at low shear rates while having minimal impact at high shear rates. Aside from the added cost and formulation complexity, such additives may have a negative impact on the product aesthetics, e.g. forming an insoluble layer on the water surface in a toilet bowl or sticking to the hard surface to the point where it is difficult to rinse it away. Building the specified rheology with such a “filled” viscoelastic system is therefore not desirable.
Advantageously, the compositions of the invention are also suitable for the bleaching of different types of surfaces including hard-surfaces like floors, walls, tiles, glass, kitchen surfaces, bathrooms surfaces, toilet bowls and/or dishes and the like as well as fabrics. It is therefore an object of the present invention to provide a bleach-containing cleaning composition for use on a cleaning substrate that overcomes the disadvantages and shortcomings associated with prior art cleaning compositions for cleaning hard surfaces.